POLYMER COMPOSITION CONTAINING PLLA AND PDLA

Description

[0001] The invention relates to a polymer composition and a process for its production. Furthermore, the invention relates to the use of the polymer composition in a process for producing films, molded parts, or fibers from the polymer composition, as well as such products containing the polymer composition according to the invention.

[0002] From the perspective of conserving fossil resources, waste disposal, and reducing CO2 emissions, it is desirable to replace the widely used conventional plastics based on fossil raw materials with plastics that can be derived at least partially or entirely from renewable resources. Polymers that are based at least partially or entirely on renewable resources are also called "bio-based" polymers.

[0003] Biodegradable plastics are not necessarily bio-based. For example, some plastics made from fossil, non-renewable resources are biodegradable. Biodegradability is not tied to the raw material source, but depends solely on the chemical structure of the material and its ability to be transformed into naturally occurring metabolic end products through biological activity.

[0004] Several polymer compositions are now available that are both fully biodegradable and bio-based. One such thermoplastic polymer composition, particularly suitable for blown film extrusion, flat film extrusion, and injection molding of fully biodegradable products, is commercially available under the trade name "BIOPLAST®<500" from BIOTEC GmbH & Co. KG in Emmerich, Germany.

[0005] To expand the application possibilities of fully biodegradable, bio-based polymer compositions, increased heat resistance of the films, molded parts or fibers obtainable from the plastics is particularly desirable.

[0006] Many food products are filled at temperatures above 70°C. Examples include hot drinks like coffee or tea, but also condiments like ketchup. The latter are also pasteurized during the hot filling process.

[0007] Currently, containers made of polystyrene or polypropylene are most commonly used to hold these hot foods. While these plastics have sufficiently high heat resistance, they are neither biodegradable nor bio-based. Conversely, most of the biodegradable, bio-based plastics available today do not have sufficient heat resistance to be used for this purpose.

[0008] Polylactic acid (PLA) is a polymer frequently used in biodegradable, bio-based plastics. PLA is a polymer composed of lactic acid monomers and can be amorphous, semicrystalline, or crystalline, depending on its composition. It contains two different lactic acid monomers, D-lactic acid and L-lactic acid, which are stereoisomeric. PLA typically contains both D- and L-lactic acid monomers, and the ratio of these two monomers significantly influences its properties. Due to its glass transition temperature of approximately 55°C, PLA softens rapidly at temperatures above 55°C, which negatively impacts its use at these temperatures for manufacturing molded parts, for example, using injection molding.Similarly, PLA-based compounds have low heat resistance, which, however, can increase significantly above PLA's glass transition temperature with increasing PLA crystallinity. PLA-based compounds with a high degree of PLA crystallinity can therefore only be used for a maximum of approximately 5 minutes at temperatures above their glass transition temperature. It should be noted, however, that PLA crystallization is a slow process that also requires heating, which complicates the commercial application of PLA.

[0009] Various methods for increasing the degree of crystallinity and accelerating the crystallization of PLA are known in the prior art. One method currently in use involves the application of mixtures of two different PLA grades, each consisting of at least 95% L-lactic acid monomers or D-lactic acid monomers. These two grades are accordingly referred to as poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA). It is known that PLLA and PDLA in their mixtures arrange themselves into specific, three-dimensional stereocomplexes, resulting in extremely stable crystals with melting points well above 200°C.

[0010] Thus, in EP 2 116 575 A1, the production of PDLA / PLLA mixtures in a preferred ratio of 40 wt.% to 60 wt.% to 60 wt.% to form stereocomplexes with a high melting point is described to a high degree, but this leads to expensive polymer compositions due to the high price of PDLA.

[0011] US Patent 2008 / 0097074 A1 describes the preparation of PDLA / PLLA mixtures which, upon addition of a urea-based nucleating agent, result in the formation of stereocomplexes with a high melting point. US Patent 2008 / 0097074 A1 particularly favors the use of PLLA and PDLA in ratios of 40 wt.% to 60 wt.% to 60 wt.% to 40 wt.%, which, however, leads to expensive polymer compositions due to the high price of PDLA. Furthermore, a very specific nucleating agent must be used.

[0012] WO 2013 / 062412 A2 also describes the production of PDLA / PLLA mixtures that exhibit a high degree of stereocomplexes and have a high melting point as well as increased heat stability. However, the ratio of PDLA to PLLA is not specified.

[0013] The compositions known from the prior art have in common that they either use a very high PDLA content or do not specify the ratio of PDLA to PLLA. Furthermore, the compositions described in the prior art consist almost exclusively of PDLA and PLLA, which are expensive raw materials.

[0014] JP 2003 128900 A discloses a polymer composition containing polylactic acid, a polyester based on adic and succinic acid, and an inorganic filler.

[0015] Based on the prior art described above, one object of the invention was to provide a cost-effective and / or biodegradable polymer composition based on polylactic acid. Preferably, the polymer composition should enable the simple and / or economical production of molded parts, films, or fibers. Production preferably takes place using economical processes. The molded parts, films, or fibers made from the polymer composition preferably exhibit high heat resistance in accordance with DIN EN ISO 75, Method B. A further object of the invention was to provide a polymer composition that is largely produced from renewable raw materials. Preferably, the polymer composition has all of the aforementioned features in common.

[0016] This problem is solved according to the invention by the polymer composition specified in claims 1 and 8, the method specified in claim 7, the method specified in claim 9, the use specified in claim 11 and the products mentioned in claim 12.

[0017] Advantageous embodiments of the invention are specified in the dependent claims and are explained in detail below, as is the general concept of the invention.

[0018] The polymer composition according to the invention contains, based on the total weight of the polymer composition, the following components: a. 35 to 60 wt.% PLLA, b. 0.1 to 15 wt.% PDLA, c. 5 to 40 wt.% polyester, d. 5 to 40 wt.% organic or inorganic filler, wherein component c. is a statistical copolyester based on at least adipic and / or sebacic acid.

[0019] A key feature of the polymer composition according to the invention is the use of a small proportion of PDLA, from 0.1 to 15 wt.%, in combination with 5 to 40 wt.% of a polyester and 5 to 40 wt.% of an organic or inorganic filler. Surprisingly, it has been found that in the polymer composition according to the invention, the use of small amounts of PDLA together with a polyester and an organic or inorganic filler is sufficient to obtain a polymer composition that exhibits high heat resistance according to DIN EN ISO 75, Method B, and / or is biodegradable and / or consists mainly of bio-based carbon and / or has good mechanical properties.

[0020] Without being bound to any specific scientific theory, it appears that even the addition of a small amount of PDLA in combination with a polyester and a filler leads to extensive crystallization of the polylactic acid, forming a high number of stereocomplexes with a high melting point. Polymer compositions according to the invention can also be used for applications involving temperatures above 55°C. The fact that even a small amount of PDLA, in combination with a polyester and a filler, leads to polymer compositions with high heat resistance is surprising, since compositions with a high PDLA content are primarily known from the prior art.

[0021] According to the invention, the polymer composition contains 3 to 20 wt.%, preferably 5 to 15 wt.%, of PDLA, based on the total amount of PDLA and PLLA components present. The low proportion of PDLA reduces the cost of the polymer composition while maintaining good heat resistance and / or good mechanical properties. When using less than 3 wt.% PDLA, based on the total amount of PDLA and PLLA components present in the polymer composition, crystallization is insufficient; when using more than 20 wt.%, the polymer composition becomes difficult to process.

[0022] The polymer composition preferably contains 7 to 13 wt.% PDLA, based on the total amount of PDLA and PLLA components in the polymer composition. It has been found that such amounts of PDLA, relative to the total amount of PDLA and PLLA, result in polymer compositions that are particularly well-suited for further processing. In particular, such polymer compositions allow for short cycle times in injection molding while maintaining good heat resistance.

[0023] As explained at the outset, the purity of the components PLLA and PDLA is determined by the content of L-lactic acid monomers (for PLLA) or D-lactic acid monomers (for PDLA). According to the invention, the component PLLA preferably contains at least 90% L-lactic acid monomers. Optimal results are achieved when the component PLLA contains at least 94%, and in particular at least 98% or 99%, L-lactic acid monomers. According to the invention, the component PDLA preferably contains at least 90% D-lactic acid monomers. Optimal results are achieved when the component PDLA contains at least 94%, and in particular at least 98% or 99%, D-lactic acid monomers.

[0024] According to a further embodiment of the invention, the polymer composition contains 45 to 60 wt.% PLLA, based on the total weight of the polymer composition. Tests have shown that if less than 15 wt.% PLLA, based on the total weight of the polymer composition, is used, a material with insufficient heat resistance is obtained; if more than 70 wt.%, based on the total weight of the polymer composition, is used, the resulting material is too brittle for most practical applications.

[0025] Preferably, the polymer composition contains, based on the total weight of the polymer composition, 5 to 35 wt.%, particularly preferably 15 to 25 wt.% of an organic or inorganic filler.

[0026] Preferred inorganic or organic fillers according to the invention are selected from the group consisting of chalk, lime, talc, calcium carbonate, titanium dioxide, aluminum oxide, magnesium oxide, silicates, kaolin, dolomite, boron nitride, terbium oxide, starch, modified starch, thermoplastic starch, cellulose, cyclodextrins, saccharin, thymine, uracil, orotic acid, cyanuric acid, polyvinyl alcohol, polyhydroxyalkanoates, polyhydroxybutyrate, polybutylene succinate, polybutylene terephthalate, Ecoflex and mixtures thereof.

[0027] In a further advantageous embodiment of the invention, the polymer composition contains, based on the total weight of the polymer composition, 5 to 35 wt.%, preferably 10 to 30 wt.%, more preferably 15 to 25 wt.% of a polyester.

[0028] The diol component is formed by alkanediols with 2 to 12 carbon atoms in the carbon chain. Ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol are preferred. Alternatively, alkenediols with 4 to 12 carbon atoms in the carbon chain are used. 1,4-Butenediol, pent-2-ene-1,5-diol, and 3-methyl-2-pentene-1,5-diol are preferred. Other diols, such as neopentyl glycol, 1,4- or 1,3-dimethylolcyclohexane, or mixtures thereof, may also be included.

[0029] According to a further embodiment of the invention, the polyester is an ester based on adipic acid and 1,4-butanediol.

[0030] According to the invention, the polyester is a statistical copolyester based on at least adipic or sebacic acid.

[0031] According to a further preferred embodiment of the invention, the polyester is a statistical aliphatic-aromatic copolyester based on 1,4-butanediol, adipic acid and / or sebacic acid and terephthalic acid or a terephthalic acid derivative, in particular dimethyl terephthalate (DMT). This can, in particular, have a glass transition temperature of -25 to -40°C, especially -30 to -35°C, and / or a melting range of 100 to 120°C, especially 105 to 115°C.

[0032] According to a further embodiment of the invention, the polymer composition according to ASTM 6866 contains at least 40%, preferably 50%, more preferably 60% bio-based carbon.

[0033] According to the invention, the polymer composition is biodegradable according to EN 13432, preferably completely biodegradable.

[0034] The special thermal properties of the polymer composition according to the invention can be readily demonstrated using differential scanning calorimetry (DSC). When a polymer sample is subjected to a defined heating / cooling program, phase transitions associated with energy changes (glass transition, crystallization, melting, etc.) are recorded in DSC diagrams as exothermic (e.g., crystallization) or endothermic (e.g., melting) peaks. The appearance of a peak in the DSC measurement therefore requires that the phase transition occurs during the measurement, i.e., while the temperature program is being executed. Thus, an amorphous sample that crystallizes during heating will produce an exothermic peak during the heating phase.Depending on the number and type of phase transitions that occur during the temperature program, a corresponding number of exothermic and endothermic peaks result, with the glass transition temperature appearing not as a peak but as a step. A temperature program consisting of a heating-cooling-heating cycle is typically used for the measurement. In this program, the sample is first equilibrated at a preset initial temperature for 2 to 5 minutes. After this initial equilibration phase, the sample is heated at a constant rate to a preset first target temperature. A heating rate of 10°C / min is typically used. At the first target temperature, the sample is equilibrated again for 2 to 5 minutes and then cooled at a constant rate to a preset second target temperature. A cooling rate of 10°C / min is also typically used.At the second target temperature, the sample is equilibrated again for 2 to 5 minutes and then heated at a constant rate to a preset third target temperature, at which the sample is held for 2 to 5 minutes before the measurement is terminated. Typically, the same heating rate as in the first heating phase is used, e.g., 10°C / min. The first and third target temperatures can be the same or different, as can the initial and second target temperatures.

[0035] According to a further embodiment of the invention, in a DSC diagram of the polymer composition, which was measured in a heating-cooling-heating cycle starting at an initial temperature of 15°C with target temperatures of 220°C-15°C-260°C with heating and cooling rates of 10°C / min each and equilibration times at the target temperatures of 5 min each, an exothermic peak in a temperature range of 80°C to 120°C, preferably from 90°C to 110°C, occurs in the cooling phase, particularly in the cooling phase to the second target temperature, in a DSC diagram of the polymer composition, which was measured in a heating-cooling-heating cycle starting at an initial temperature of 15°C with target temperatures of 220°C-15°C-260°C with heating and cooling rates of 10°C / min each and equilibration times at the target temperatures of 5 min each.

[0036] In a further embodiment of the invention, a DSC diagram of the polymer composition, measured in a heating-cooling-heating cycle starting at an initial temperature of 15°C with target temperatures of 220°C-15°C-260°C at heating and cooling rates of 10°C / min and equilibration times of 5 min at each target temperature, shows an endothermic peak in the second heating phase at temperatures above 200°C, preferably above 210°C, and even more preferably above 215°C. The endothermic peak above 200°C can also occur in the first heating phase.

[0037] In a further preferred embodiment of the invention, a further endothermic peak occurs in the first, the second or in both heating phases at temperatures of 140°C to 190°C.

[0038] The polymer composition according to the invention may contain, in addition to the main components PLLA, PDLA, polyester and organic or inorganic filler, further components, in particular further polymers and / or conventional additives, such as processing aids, plasticizers, stabilizers and / or flame retardants.

[0039] In particular, the polymer composition according to the invention can contain polycaprolactone. The mechanical properties of the polymer composition can be advantageously influenced by the addition of polycaprolactone.

[0040] According to a preferred embodiment of the invention, the polymer composition has a water content of less than 0.1 wt.%, in particular less than 0.05 wt.% or 0.04 wt.%, in each case based on the total weight of the polymer composition. Practical tests have shown that water contents of less than 0.1 wt.% can reduce the undesirable degradation of the polymer composition according to the invention during subsequent processing.

[0041] The invention further provides methods by which it is possible to obtain the polymer compositions described above.

[0042] Basically, the methods according to the invention comprise the following steps, wherein the individual steps can be carried out simultaneously or successively and in any order and frequency: a. Producing a mixture containing, based on the total weight of the mixture, at least the following components: i. 15 to 70 wt.% PLLA, ii. 0.1 to 15 wt.% PDLA, iii. 5 to 40 wt.% polyester, iv. 5 to 40 wt.% organic or inorganic filler. b. Homogenizing the mixture by supplying thermal and / or mechanical energy, wherein the polymer composition contains 35 to 60 wt.% of component a., based on the total weight of the polymer composition, and the polyester according to component iii is a statistical copolyester based on at least adipic and / or sebacic acid.

[0043] Preferably, the process steps are carried out in the order given above.

[0044] The process according to the invention provides for the homogenization of the mixture. Homogenization can be carried out by any measures familiar to those skilled in the art of plastics engineering. Preferably, the mixture is homogenized by dispersion, stirring, kneading, and / or extrusion. According to a preferred embodiment of the invention, shear forces act on the mixture during homogenization. Suitable manufacturing processes for PDLA / PLLA mixtures, which are also analogously applicable to the production of the polymeric material according to the invention, are described, for example, in EP 2 116 575 A1.

[0045] According to a preferred embodiment of the invention, the mixture is heated during homogenization (e.g. in an extruder or in a melting kneader), preferably to a temperature of 60°C to 250°C, in particular from 90°C to 200°C.

[0046] The above statements regarding the components of the polymer composition preferably also apply equally to the components of the process according to the invention.

[0047] According to a preferred embodiment of the process according to the invention, the water content of the polymer composition is adjusted to less than 0.1 wt.%, in particular less than 0.05 wt.% or 0.04 wt.%, in each case based on the total weight of the polymer composition. The water contents specified here refer to the material obtained after homogenization, in particular the material exiting the extruder. To determine the water content, a sample of the molten, homogenized material is collected in a sealable container directly after homogenization (i.e., typically immediately after exiting the extruder), and the container is sealed airtight. Care must be taken to ensure that the container is filled as completely as possible with homogenized material to minimize air entrapment.After the sealed container has cooled, it is opened, a sample is taken, and the water content is determined using Karl Fischer titration.

[0048] Preferably, the water content is adjusted by drying during homogenization. The drying process can be carried out, for example, by degassing the mixture or the melt, advantageously by removing water vapor during homogenization or extrusion.

[0049] Furthermore, the invention provides methods by which it is possible to obtain molded parts, films or fibers from the polymer compositions described above.

[0050] Basically, the inventive method for manufacturing molded parts comprises the following steps: a. Introducing a polymer composition described above into a mold; b. Shaping the molded part; and c. Removing the molded part from the mold.

[0051] These steps together form a cycle, which is typically carried out within a specific time, the cycle time, and can be repeated as often as desired. It has proven advantageous if the mold into which the polymer composition is introduced in step a. of the process for producing molded parts, films, or fibers is heated to 30 to 130°C, preferably 30 to 100°C, and more preferably 45 to 85°C, and is essentially maintained at this temperature during the process. Products manufactured with one of the polymer compositions described above and the aforementioned process crystallize rapidly and to such a high degree that they exhibit increased heat resistance and can also be used at temperatures above the glass transition temperature of PLA.Using a suitably tempered mold promotes the crystallization rate, so that the molded parts can be removed from the mold after a shorter time without deforming.

[0052] For economic and process-related reasons, it has proven advantageous if the process for manufacturing molded parts is carried out within a cycle time of a maximum of 60 seconds, preferably a maximum of 45 seconds, and more preferably a maximum of 30 seconds. This increases the production capacity and cost-effectiveness of the process.

[0053] The polymer compositions according to the invention are suitable for a wide variety of purposes. In particular, the compositions are suitable for the production of molded parts, films, or fibers. Due to their rapid crystallization, the compositions are especially suitable for the production of molded parts. Accordingly, the invention also relates to molded parts, films, and fibers produced from the polymer compositions according to the invention.

[0054] The above statements regarding heat resistance, biodegradability, and the bio-based carbon content of the polymer composition apply equally to the molded parts according to the invention. Thus, an advantageous embodiment of the invention provides that the molded parts, films, or fibers are heat-resistant up to 55°C, preferably up to 65°C, more preferably up to 70°C, even more preferably up to 75°C, even more preferably up to 80°C, even more preferably up to 85°C, even more preferably up to 90°C, even more preferably up to 95°C, according to DIN EN ISO 75, Method B, and / or are biodegradable according to EN 13432, preferably completely biodegradable, and / or contain at least 50% bio-based carbon according to ASTM 6866.

[0055] Due to their high heat resistance, molded parts made from the polymer composition according to the invention are ideally suited as containers or capsules for coffee in the corresponding coffee preparation systems. One such particularly preferred embodiment of the molded parts according to the invention is described in more detail below with reference to the following drawings. Fig. 1 shows a schematic top view of a particularly preferred embodiment of the molded parts according to the invention. Fig. 2 shows a schematic cross-sectional view of a particularly preferred embodiment of the molded parts according to the invention. Fig. 3 shows a DSC diagram of formulation A from Example 1 (comparative example). Fig. 4 shows a DSC diagram of formulation B from Example 2.

[0056] Figure 1Figure 1 shows a top view of a particularly preferred embodiment 1 of the molded parts according to the invention, comprising a frustoconical body 2 with a rim 3, a side wall 4, an inlet wall 5, wherein the inlet wall 5 may comprise a flat or convex part 6, and a lower feed wall 7 that seals the rim 3, wherein the flat or convex portion 6 has a recessed or relief-like structure 8, wherein this recessed or relief-like structure 8 facilitates the penetration of this structure with blades belonging to the injection device and is located on a substantially circular path 9, the diameter of which is defined by the diameter of the blades which are also arranged circularly.

[0057] Figure 2Figure 1 shows a cross-section of a particularly preferred embodiment 1 of the molded parts according to the invention, comprising a frustoconical body 2 with a rim 3, a side wall 4, an inlet wall 5, wherein the inlet wall 5 may comprise a flat or convex part 6, and a lower feed wall 7 that seals the rim 3, wherein the flat or convex portion 6 has a recessed or relief-like structure 8, wherein this recessed or relief-like structure 8 facilitates the penetration of this structure with blades belonging to the injection device and is located on a substantially circular path, the diameter of which is defined by the diameter of the blades which are also arranged circularly.

[0058] According to a preferred embodiment of the molded parts according to the invention, the lower feed wall 7 seals the edge 3 of the capsule in a substantially gas-tight manner. An advantage of this embodiment is that the shelf life of oxidizable substances contained in the capsule is extended by the gas-tight packaging.

[0059] In a further preferred embodiment of the molded parts according to the invention, the lower feed wall 7 is biodegradable according to EN 13432, preferably completely biodegradable, so that this embodiment of the molded parts according to the invention is biodegradable in its entirety.

[0060] The films according to the invention can be blown, flat, or cast films. Preferred film thicknesses for blown films according to the invention are from 0.012 to 0.1 mm, for flat films according to the invention from 0.15 to 0.5 mm, and for cast films according to the invention from 0.01 to 0.5 mm.

[0061] The principle of the invention will be explained in more detail below using examples.

[0062] The following materials were used for the comparison and implementation examples: Polylactic acid, PLA (INGEO 2003D, NATUREWORKS); Poly(butylene adipate co-terephthalate), PBAT (ECOFLEX F Blend C 1201, BASF); Calcium carbonate (HYDROCARB, OMYA); PLLA (SYNTERRA PLLA 1510, SYNBRA); PDLA (SYNTERRA PDLA 1010, SYNBRA). Example 1 (comparative example):

[0063] Using a twin-shaft extruder (co-rotating extruder) of the type Werner & Pfleiderer (COPERION) ZSK 40, screw diameter 40 mm, L / D = 42, the following formulation was compounded (dosed proportions in mass percent): Formulation A: 59.4% by weight PLA 22.9% by weight PBAT 17.7% by weight CaCO 3

[0064] The following compounding parameters were adhered to: Tab. 1: Temperaturprofil ZSK 40 Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 nozzle 25°C 170°C 170°C 170°C 170°C 170°C 170°C 170°C 168°C Melting temperature at nozzle exit: 165°C Speed: 180 min -1< throughput 40 kg / h Degassing no

[0065] A DSC diagram of recipe A is in Figure 3 shown. A striking feature of the DSC diagram in Figure 3 These are the absence of peaks in the cooling phase to the second target temperature and the absence of peaks above 200°C.

[0066] The granules were processed into test specimens in an ARBURG ALLROUNDER 270 M injection molding machine.

[0067] The following processing parameters were set: Table 2: Processing parameters for injection molding Zone 1 Zone 2 Zone 3 Zone 4 25°C 180°C 180°C 180°C Tool temperature: 55°C Cycle time: 25 s

[0068] The test specimens obtained were characterized by low heat resistance at temperatures above 55°C.

[0069] The mechanical properties of the test specimens were determined after a storage period of 24 hours at room temperature and ambient atmosphere as follows: Table 3: Mechanical properties of the test specimens after 24 h E-modulus [GPa] EN ISO 527 Tensile strength [MPA] EN ISO 527 Elongation at tensile strength [%] EN ISO 527 Breaking stress [MPa] EN ISO 527 Impact strength at 23°C [kJ / m²<] EN ISO 179 / 1 Flexural strength [MPa] EN ISO 178 Bending modulus [GPa] EN ISO 178 2,4 28 2 34 140 60 2,5 Example 2:

[0070] Using a twin-shaft extruder (co-rotating extruder) of the type Werner & Pfleiderer (COPERION) ZSK 40, screw diameter 40 mm, L / D = 42, the following formulation was compounded (dosed proportions in mass percent): Formulation B: 53.5 wt.% PLLA 5.9 wt.% PDLA 22.9 wt.% PBAT 17.7 wt.% CaCO3

[0071] The following compounding parameters were adhered to: Tab. 4: Temperaturprofil ZSK 40 Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 nozzle 25°C 170°C 170°C 170°C 170°C 170°C 170°C 169°C 167°C Melting temperature at nozzle exit: 165°C Speed: 185 min -1< throughput 41 kg / h Degassing no

[0072] A DSC diagram of recipe B is in Figure 4 shown. Noticeable feature of the DSC diagram of formula B in Figure 4 The exothermic peak occurs during the cooling phase to the second target temperature (at approximately 40 min) in a temperature range of 90 to 110°C, and the endothermic peak occurs during the second heating phase (at approximately 74 min) in a temperature range of 220 to 240°C.

[0073] The granules were processed into test specimens in an ARBURG ALLROUNDER 270 M injection molding machine.

[0074] The following processing parameters were set: Table 5: Processing parameters for injection molding Zone 1 Zone 2 Zone 3 Zone 4 25°C 180°C 180°C 180°C Tool temperature: 55°C Cycle time: 20 s

[0075] The test specimens obtained were characterized by increased heat resistance at temperatures above 55°C and up to 95°C.

[0076] The mechanical properties of the test specimens were determined after a storage period of 24 hours at room temperature and ambient atmosphere as follows: Table 6: Mechanical properties of the test specimens after 24 h E-modulus [GPa] EN ISO 527 Tensile strength [MPA] EN ISO 527 Elongation at tensile strength [%] EN ISO 527 Breaking stress [MPa] EN ISO 527 Impact strength at 23°C [KJ / m2] EN ISO 179 / 1 Biegefestigkeit [MPa] EN ISO 178 Biegemodul [GPa] EN ISO 178 2,4 31 2 30 80 53 2,5

[0077] A striking feature when comparing the results of the two compositions, compiled in Tables 3 and 6 as well as in the DSC diagrams in Fig. 3 and 4The strikingly better thermal properties of formulation B are particularly evident in the DSC diagram, manifested primarily as an exothermic crystallization peak during the cooling phase in the temperature range of 90°C to 110°C and a higher melting point in the temperature range of 220°C to 240°C. These two peaks are absent in the DSC diagram of formulation A, indicating slower crystallization and the lack of formation of stereocomplexes of PLLA and PDLA. Consistent with the DSC measurements, formulation A exhibits a noticeably higher impact strength, presumably due to a lower degree of crystallinity in the specimen made from formulation A. Despite the higher degree of crystallinity in the specimen made from formulation B and the resulting improved thermal properties, molded parts made from formulation B still possess very good, and in some cases even slightly improved, mechanical properties compared to formulation B, such as...This can be seen in the increased tensile strength.

[0078] The invention has been described above by way of example. It is understood that the invention is not limited to the described embodiments. Rather, the invention offers a wide range of possibilities for adaptation and modification, and the scope of protection of the invention is defined by the following patent claims.

Claims

1. Polymer composition containing, based on the total weight of the polymer composition, the following components: a. 35 to 60 wt.% PLLA, b. 0.1 to 15 wt.% PDLA, c. 5 to 40 wt.% polyester, d. 5 to 40 wt.% organic or inorganic filler, characterized in that component c. is a statistical copolyester based on at least adipic and / or sebacic acid.

2. Polymer composition according to claim 1, characterized in that the polymer composition contains 3 to 20 wt.%, in particular 5 to 15 wt.%, PDLA, based on the total amount of the components PDLA and PLLA contained in the polymer composition; and / or in that the polymer composition contains 45 to 60 wt.% of component a., in each case based on the total weight of the polymer composition; and / or in that the polymer composition contains 5 to 35 wt.%, 10 to 30 wt.% or 15 to 25 wt.% of component c., in each case based on the total weight of the polymer composition; and / or in that the polymer composition contains 5 to 35 wt.% or 15 to 25 wt.% of component d., in each case based on the total weight of the polymer composition.

3. Polymer composition according to either of the preceding claims, characterized in that component c. is a statistical aliphatic-aromatic copolyester based on 1,4-butanediol, adipic acid and / or sebacic acid and terephthalic acid or terephthalic acid derivative, in particular dimethyl terephthalate DMT.

4. Polymer composition according to any of the preceding claims, characterized in that component d. is selected from the group consisting of chalk, lime, talc, calcium carbonate, aluminum oxide, magnesium oxide, silicates, kaolin, dolomite, boron nitride, terbium oxide, starch, modified starch, thermoplastic starch, cellulose, cyclodextrins, saccharin, thymine, uracil, orotic acid, cyanuric acid, polyvinyl alcohol, polyhydroxyalkanoates, polyhydroxybutyrate, polybutylene succinate, polybutylene terephthalate, Ecoflex and mixtures thereof.

5. Polymer composition according to any of the preceding claims, characterized in that the polymer composition according to ASTM 6866 contains at least 40%, 50%, or 60% bio-based carbon; and / or in that the polymer composition according to EN 13432 is biodegradable, in particular completely biodegradable.

6. Polymer composition according to any of the preceding claims, characterized in that in a DSC diagram of the polymer composition, which was measured in a heating-cooling-heating cycle starting at 15°C with target temperatures 220°C-15°C-260°C with heating and cooling rates of 10°C / min each and equilibration times at the target temperatures of 5 min each, an exothermic peak occurs in the cooling phase in a temperature range from 80°C to 120°C, especially from 90°C to 110°C; and / or in that in a DSC diagram of the polymer composition, which was measured in a heating-cooling-heating cycle starting at 15°C with target temperatures 220°C-15°C-260°C with heating and cooling rates of 10°C / min each and equilibration times at the target temperatures of 5 min each, an endothermic peak occurs in the second heating phase at temperatures above 200°C, in particular above 210°C or 215°C, with optionally another endothermic peak occurring in the heating phases at temperatures from 140°C to 190°C.

7. Method for producing a polymer composition according to any of claims 1 to 6, characterized by: a. producing a mixture containing, based on the total weight of the mixture, at least the following components: i. 15 to 70 wt.% PLLA, ii. 0.1 to 15 wt.% PDLA, iii. 5 to 40 wt.% polyester, iv. 5 to 40 wt.% organic or inorganic filler; b. homogenizing the mixture using thermal and / or mechanical energy; characterized in that the polymer composition contains 35 to 60 wt.% of component a., based on the total weight of the polymer composition, and in that the polyester according to component iii is a statistical copolyester based on at least adipic and / or sebacic acid.

8. Polymer composition obtainable by a method according to claim 7.

9. Method for producing molded parts, characterized by: a. introducing a polymer composition according to any of claims 1 to 6 or 8 into a mold; b. molding the molded part; and c. removing the molded part from the mold.

10. Method according to claim 9, characterized in that the mold into which the polymer composition is introduced in step a. is heated to 30 to 130°C, 30 to 100°C, or 45 to 85°C and is substantially maintained at this temperature during the method; and / or in that a cycle comprising steps a. to c. of the method is carried out within a cycle time of no more than 60 seconds, in particular no more than 45 or 30 seconds.

11. Use of a polymer composition according to any of claims 1 to 6 or 8 for producing molded parts, films or fibers.

12. Molded parts, films or fibers containing a polymer composition according to any of claims 1 to 6 or 8.

13. Molded part according to claim 12, characterized in that the molded part is heat-resistant according to DIN EN ISO 75, method B, up to 55°C, in particular up to 80°C or 85°C or 90°C or 95°C and / or is completely biodegradable according to EN 13432 and / or contains at least 50% bio-based carbon according to ASTM 6866; and / or in that the molded part (1) comprises a frustoconical body (2) with an edge (3), a side wall (4), an inlet wall (5), the inlet wall (5) comprising a flat or convex portion (6), a lower supply wall (7) which seals the edge (3), the flat or convex portion (6) having a recessed or relief-like structure (8), this recessed or relief-like structure (8) facilitating the penetration of this structure by blades belonging to the injection device and being located on a substantially circular path (9) the diameter of which is defined by the diameter of the blades also arranged in a circular manner.

14. Molded part according to claim 13, characterized in that the lower supply wall (7) seals the edge (3) in a substantially gas-tight manner.

15. Molded part according to claim 13 or claim 14, characterized in that the lower supply wall (7) is biodegradable, in particular completely biodegradable, according to EN 13432.